Ulam stability problem for quadratic mappings of Euler–Lagrange Original Research Article

The purpose of this paper is to solve the stability problem of Ulam for an approximate mapping f:A→Bf:A→B of the following quadratic functional equation of Euler–Lagrange (a+b)aQ(x)+(a+b)bQ(y)=Q(ax+by)+abQ(x-y)(a+b)aQ(x)+(a+b)bQ(y)=Q(ax+by)+abQ(x-y) Turn MathJax on for all View the MathML sourcex,y∈A with AA and BB linear spaces.